refactor: simplify normalizeTypes function (#6097)

Author: Ayoub-Mabrouk

lib/utils.js

@@ -70,16 +70,11 @@ exports.normalizeType = function(type){
  * @api private
  */
 
-exports.normalizeTypes = function(types){
-  var ret = [];
-
-  for (var i = 0; i < types.length; ++i) {
-    ret.push(exports.normalizeType(types[i]));
-  }
-
-  return ret;
+exports.normalizeTypes = function(types) {
+  return types.map(exports.normalizeType);
 };
 
+
 /**
  * Parse accept params `str` returning an
  * object with `.value`, `.quality` and `.params`.